The invention relates to a spinning rotor for an open-end spinning device of the type having a shaft supporting a rotor dish (rotor) and a method of making same. The rotor includes a sliding wall starting at the open face side of the rotor and widening conically in the rotor axial direction to a position where it connects with a fiber collecting groove forming the greatest inner diameter of the rotor.
The inner surfaces of spinning rotors are commonly manufactured by means of machine tool cutting operations. Since these rotor surfaces should exhibit good sliding characteristics for the fiber material to be processed, they require polishing. Usually a diamond polishing or lapping compound is utilized. The finishing of the inner surfaces, especially of the area of the fiber collecting groove, and thereby the preciseness of the shape has a great influence on the yarn being spun. On the other hand, the inner surfaces of the rotors, especially in the area of the fiber collecting groove, are to exhibit a high wear resistance so that the spinning rotor has a sufficient lifetime and retains its desired shape/form over the maximum possible running period. For this purpose, it has been contemplated to provide either rotors made of aluminum with different coatings, or steel rotors that are treated by a hardening process. In all instances, however, the service life was unsatisfactory. Furthermore, the surface finishing of the rotors was adversely affected due to this additional treatment, so that the spinning quality was compromised in favor of the increase in service life.
It is an object of this invention to provide a spinning rotor of the kind mentioned above which exhibits a high production accuracy in the area of the fiber collecting groove and an increased service life. This object is achieved according to the invention by hardening the surfaces of the fiber collecting groove by means of a plastic deformation process.
The plastic deformation of the rotor material at the surfaces of the fiber collecting grooves leads to a high measure precision in the grooves/shape and a smooth surface, while at the same time hardening the rotor material in the area of the inner surfaces of the roller. It is especially advantageous according to preferred embodiments of the invention to provide steel spinning rotors with a plastically deformed fiber collecting groove region.
In order to produce the plastic deformation of the surfaces of the fiber collecting groove, it is provided in an advantageous modification of the invention that the inner surfaces of the rotors are, subsequent to the machine tool cutting operation, exposed to a rolling or burnishing process at least in the area of the fiber collecting groove. Known burnishing processes have been utilized primarily with smooth cylindrical surfaces, especially outer cylindrical surfaces, leading to a high degree of surface finishing and a simultaneous hardening of this surface.
In order to execute the burnishing process according to a further aspect of the invention, a roller is radially pressed against the fiber collecting groove section of the rotor while the roller and rotor are rotatably driven with respect to one another. The roller has a smaller diameter than the open face side of the rotor itself and exhibits an outer profile corresponding to the desired inner profile of the fiber collecting groove in the area of the groove bottom and the adjacent surfaces. This profiled roller runs at least once over the entire circumference of the fiber collecting groove so that a uniform hardening is obtained.